Electrical stimulation
Many potential treatments for tinnitus involve the use of neurostimulation – applying small electrical currents to stimulate parts of the nervous system. In particular there is a high level of interest in transcranial direct current stimulation (tDCS), in which a constant, low current is delivered to the brain via electrodes on the scalp.

Many studies of tDCS have not involved the use of high-quality research methods, so it is good to see that the results of a randomised controlled trial (RCT) have been published. Swiss researchers [1] gave 21 people with tinnitus five tDCS sessions over five consecutive days. A further 21 people with tinnitus received ‘sham stimulation’ as a control group. Tinnitus was assessed after the final session, then one month and three months later. The assessment involved use of several accepted scales, including the Tinnitus Handicap Inventory (THI). Sadly, comparing the treatment and control groups, led the researchers to conclude that the tDCS had no benefit.

A similar result was found by Brazilian researchers who have published a very brief account of their study [2]. Here nine people with tinnitus were given five sessions of tDCS over five days, and compared with nine who underwent a sham procedure. Tinnitus was assessed immediately before and after the treatment, using THI and one other scale. There was no difference between the two groups.

In neither of the two tDCS studies did treatment cause any harmful effects.

Magnetism can also be used to stimulate electrical activity in the brain. Transcranial magnetic stimulation (TMS), which involves a magnetic coil placed near the head, has received attention from scientists as a possible tinnitus treatment. One recent study carried out in Turkey [3] involved 75 people with tinnitus divided into five groups of 15. In Groups 1 and 2, participants received repetitive TMS (rTMS), given at two different frequencies. Group 3 received the same rTMS as Group 1 plus paroxetine, a drug commonly used as an antidepressant. Group 4 had paroxetine only. Group 5 was a control group receiving sham rTMS.

The researchers used the THI and the Tinnitus Severity Index (TSI), plus other scales, to measure the level of tinnitus before treatment, and one and six months after. The THI and TSI scores improved after treatment in all groups, except the control group. The differences between the four groups receiving active treatment were found to be not statistically significant. A few study participants reported treatment side effects, but these were mild and short-term. The study authors concluded that rTMS and paroxetine, used together or separately, have potential for tinnitus treatment.

The number in each study group is, however, small and further research with more patients (including larger control groups) over a longer period of time is now necessary. There have been previous studies with paroxetine which have not shown it to be effective for tinnitus.

TMS has also recently been studied in an RCT [4] by a team in the USA. They gave 35 people with tinnitus rTMS every day for 10 days, with a further 35 receiving sham treatment. Their primary measure of tinnitus was the Tinnitus Functional Index (TFI), which they used with their participants immediately after treatment and then at intervals over the next six months. Over half of those receiving TMS (56%) were considered to have benefited from the treatment, compared with just 22% of the control group. While the results from this well conducted study are encouraging, the researchers point out that this is a small study and that many questions regarding TFI remain unanswered. They want to see bigger studies that address these questions.

Sadly, we do not have full access to a recent rTMS study conducted by Korean researchers [5] but it appears that working with 14 patients (no control group) they found an improvement in THI using one frequency level but not with another.

Could electrical stimulation, not of the brain itself but of the vagus nerves, offer a way forward? A Finnish team has completed a very preliminary study [6], in which they gave transcutaneous vagus nerve stimulation (tVNS) to seven people with tinnitus and to eight people without the condition. From previous research, they were aware that certain types of electrical activity in the brain (beta-band and gamma-band activity) is usually greater in those who have tinnitus. They confirmed this to be the case in their own study. The administration of tVNS was found by the researchers to ‘modulate’ (i.e. exert a controlling influence) on beta and gamma-band activity. They did not study the effects of tVNS on tinnitus symptoms but their findings suggest that tVNS does deserve further investigation.

DrugsBenzodiazepines are sometimes given for tinnitus. This category of drugs, which includes for example diazepam, have been widely used since the 1970s as short-term treatments for anxiety. However, there have always been concerns about their side effects and they are one of the most commonly abused drugs. Researchers in Australia carried out a systematic review [7] to see what evidence there was for their effectiveness against tinnitus.

They were surprised how few studies had addressed this question – just six RCTs, with a total of less than 300 tinnitus patients. Reviewing the individual studies they concluded that some of them had not been done well, so their results might be biased. Some studies had not looked at whether there were any side effects. Another problem is that different researchers used different ways of measuring tinnitus, so the study results could not be compared. Nevertheless, the reviewers felt able to conclude that there is no evidence to support the use of diazepam. There was weak evidence for the use of another drug in the same category, clonazepam, but without more (and better) trials no firm conclusions can be drawn.

Gabapentin belongs to the anticonvulsant category of drugs. Some doctors have reported that it has been of benefit to some of their tinnitus patients, but as gabapentin is known to have many side effects it can only be used in very low doses. There has already been research in which gabapentin, given in tablet form, has been combined withlidocaine (a local anaesthetic) injected direct into the middle ear, an unpleasant procedure with unacceptable side effects.

Italian researchers [8] decided to combine gabapentin with lidocaine injections given just under the skin of the ear canal. Seventy-two patients were randomly allocated to receive gabapentin only, gabapentin plus lidocaine, or placebo treatment. Gabapentin tablets were given every day for six weeks; lidocaine injections took place at intervals, totalling four times during the trial. Assessment of tinnitus level using THI took place before and during the treatment period, and at three and six months. The improvement in THI scores was significantly higher in the gabapentin group than in the control group, and those in the gabapentin-plus-lidocaine group did significantly better than those receiving gabapentin alone. Much more research, however, would be needed before the technique could be recommended for widespread use.

Other approaches
It is hard to turn on the radio or TV these days without hearing some mention of mindfulness, either as a treatment for some physical or psychological disorder or as a way of helping everyone to lead happier lives. Could practising mindfulness help people with tinnitus?

In a small, uncontrolled study in California [9], eight people with tinnitus attended eight group sessions of mindfulness training and were asked to continue practising for a year. All of them had improved THI scores at the end of their training and further improvements had occurred by the end of the year.

The results of surveys can often be useful in medical research, though such ‘observational’ research provides lower quality evidence than experimental studies. Over 1000 members of the American Tinnitus Association responded to a survey asking questions about their tinnitus, their quality of life and their level of physical activity [10].

Those who were most physically active were more likely to have lower levels of tinnitus distress and a better quality of life. The level of association was statistically significant. Such a finding could never prove that physical activity causes tinnitus to improve (nor how it might do so) but the authors rightly make a case for future research on exercise as a potential tinnitus treatment.

Finally, could wearing a simple ‘splint’ prosthetic in the mouth to realign the jaw be of some help? Italian researchers [11] worked with 55 patients who had tinnitus without hearing loss. They examined each patient’s temporomandibular joint (the ‘hinge’ that connects the jaw to the bones of the skull) and then fitted a splint. There was no control group.

The authors report significant improvement in THI scores after six months of splint use, the improvement being greatest in those patients whom they diagnosed as having temporomandibular disorders. They suggest that, for tinnitus patients who have no neurological or ear disorders, a temporomandibular splint might be helpful. This is an interesting but very new proposal that would need to be fully evaluated.

GlossaryPlacebo An inactive substance or other sham form of therapy administered to a patient usually to compare its effects with those of a real drug or treatment.

Randomised control trial A study in which a number of similar people are randomly assigned to 2 (or more) groups to test a specific drug or treatment. One group (the experimental group) receives the treatment being tested, the other (the comparison or control group) receives an alternative treatment, a dummy treatment (placebo) or no treatment at all. The groups are followed up to see how effective the experimental treatment was.

Statistically significant The likelihood that a result or relationship is caused by something other than random chance.

Systematic review An electronic search is done to find all the studies that have already been conducted on a precise topic. Data from good quality studies are then combined for analysis. Systematic reviews can reveal more – and provide much stronger evidence – than individual studies.

Tinnitus Functional Index; Tinnitus Handicap Inventory; Tinnitus Severity Index Questionnaires aimed at evaluating the impact of tinnitus on a person’s daily life. The different questionnaires tend to use different evaluation systems and often look at different factors which may be contributing to tinnitus distress.

Vagus nerves A pair of long nerves running from the brain to the abdomen, providing a connection between the brain to the heart, intestine and other organs.

Electrical stimulation
Many potential treatments for tinnitus involve the use of neurostimulation – applying small electrical currents to stimulate parts of the nervous system. In particular there is a high level of interest in transcranial direct current stimulation (tDCS), in which a constant, low current is delivered to the brain via electrodes on the scalp.

Many studies of tDCS have not involved the use of high-quality research methods, so it is good to see that the results of a randomised controlled trial (RCT) have been published. Swiss researchers [1] gave 21 people with tinnitus five tDCS sessions over five consecutive days. A further 21 people with tinnitus received ‘sham stimulation’ as a control group. Tinnitus was assessed after the final session, then one month and three months later. The assessment involved use of several accepted scales, including the Tinnitus Handicap Inventory (THI). Sadly, comparing the treatment and control groups, led the researchers to conclude that the tDCS had no benefit.

A similar result was found by Brazilian researchers who have published a very brief account of their study [2]. Here nine people with tinnitus were given five sessions of tDCS over five days, and compared with nine who underwent a sham procedure. Tinnitus was assessed immediately before and after the treatment, using THI and one other scale. There was no difference between the two groups.

In neither of the two tDCS studies did treatment cause any harmful effects.

Magnetism can also be used to stimulate electrical activity in the brain. Transcranial magnetic stimulation (TMS), which involves a magnetic coil placed near the head, has received attention from scientists as a possible tinnitus treatment. One recent study carried out in Turkey [3] involved 75 people with tinnitus divided into five groups of 15. In Groups 1 and 2, participants received repetitive TMS (rTMS), given at two different frequencies. Group 3 received the same rTMS as Group 1 plus paroxetine, a drug commonly used as an antidepressant. Group 4 had paroxetine only. Group 5 was a control group receiving sham rTMS.

The researchers used the THI and the Tinnitus Severity Index (TSI), plus other scales, to measure the level of tinnitus before treatment, and one and six months after. The THI and TSI scores improved after treatment in all groups, except the control group. The differences between the four groups receiving active treatment were found to be not statistically significant. A few study participants reported treatment side effects, but these were mild and short-term. The study authors concluded that rTMS and paroxetine, used together or separately, have potential for tinnitus treatment.

The number in each study group is, however, small and further research with more patients (including larger control groups) over a longer period of time is now necessary. There have been previous studies with paroxetine which have not shown it to be effective for tinnitus.

TMS has also recently been studied in an RCT [4] by a team in the USA. They gave 35 people with tinnitus rTMS every day for 10 days, with a further 35 receiving sham treatment. Their primary measure of tinnitus was the Tinnitus Functional Index (TFI), which they used with their participants immediately after treatment and then at intervals over the next six months. Over half of those receiving TMS (56%) were considered to have benefited from the treatment, compared with just 22% of the control group. While the results from this well conducted study are encouraging, the researchers point out that this is a small study and that many questions regarding TFI remain unanswered. They want to see bigger studies that address these questions.

Sadly, we do not have full access to a recent rTMS study conducted by Korean researchers [5] but it appears that working with 14 patients (no control group) they found an improvement in THI using one frequency level but not with another.

Could electrical stimulation, not of the brain itself but of the vagus nerves, offer a way forward? A Finnish team has completed a very preliminary study [6], in which they gave transcutaneous vagus nerve stimulation (tVNS) to seven people with tinnitus and to eight people without the condition. From previous research, they were aware that certain types of electrical activity in the brain (beta-band and gamma-band activity) is usually greater in those who have tinnitus. They confirmed this to be the case in their own study. The administration of tVNS was found by the researchers to ‘modulate’ (i.e. exert a controlling influence) on beta and gamma-band activity. They did not study the effects of tVNS on tinnitus symptoms but their findings suggest that tVNS does deserve further investigation.

DrugsBenzodiazepines are sometimes given for tinnitus. This category of drugs, which includes for example diazepam, have been widely used since the 1970s as short-term treatments for anxiety. However, there have always been concerns about their side effects and they are one of the most commonly abused drugs. Researchers in Australia carried out a systematic review [7] to see what evidence there was for their effectiveness against tinnitus.

They were surprised how few studies had addressed this question – just six RCTs, with a total of less than 300 tinnitus patients. Reviewing the individual studies they concluded that some of them had not been done well, so their results might be biased. Some studies had not looked at whether there were any side effects. Another problem is that different researchers used different ways of measuring tinnitus, so the study results could not be compared. Nevertheless, the reviewers felt able to conclude that there is no evidence to support the use of diazepam. There was weak evidence for the use of another drug in the same category, clonazepam, but without more (and better) trials no firm conclusions can be drawn.

Gabapentin belongs to the anticonvulsant category of drugs. Some doctors have reported that it has been of benefit to some of their tinnitus patients, but as gabapentin is known to have many side effects it can only be used in very low doses. There has already been research in which gabapentin, given in tablet form, has been combined withlidocaine (a local anaesthetic) injected direct into the middle ear, an unpleasant procedure with unacceptable side effects.

Italian researchers [8] decided to combine gabapentin with lidocaine injections given just under the skin of the ear canal. Seventy-two patients were randomly allocated to receive gabapentin only, gabapentin plus lidocaine, or placebo treatment. Gabapentin tablets were given every day for six weeks; lidocaine injections took place at intervals, totalling four times during the trial. Assessment of tinnitus level using THI took place before and during the treatment period, and at three and six months. The improvement in THI scores was significantly higher in the gabapentin group than in the control group, and those in the gabapentin-plus-lidocaine group did significantly better than those receiving gabapentin alone. Much more research, however, would be needed before the technique could be recommended for widespread use.

Other approaches
It is hard to turn on the radio or TV these days without hearing some mention of mindfulness, either as a treatment for some physical or psychological disorder or as a way of helping everyone to lead happier lives. Could practising mindfulness help people with tinnitus?

In a small, uncontrolled study in California [9], eight people with tinnitus attended eight group sessions of mindfulness training and were asked to continue practising for a year. All of them had improved THI scores at the end of their training and further improvements had occurred by the end of the year.

The results of surveys can often be useful in medical research, though such ‘observational’ research provides lower quality evidence than experimental studies. Over 1000 members of the American Tinnitus Association responded to a survey asking questions about their tinnitus, their quality of life and their level of physical activity [10].

Those who were most physically active were more likely to have lower levels of tinnitus distress and a better quality of life. The level of association was statistically significant. Such a finding could never prove that physical activity causes tinnitus to improve (nor how it might do so) but the authors rightly make a case for future research on exercise as a potential tinnitus treatment.

Finally, could wearing a simple ‘splint’ prosthetic in the mouth to realign the jaw be of some help? Italian researchers [11] worked with 55 patients who had tinnitus without hearing loss. They examined each patient’s temporomandibular joint (the ‘hinge’ that connects the jaw to the bones of the skull) and then fitted a splint. There was no control group.

The authors report significant improvement in THI scores after six months of splint use, the improvement being greatest in those patients whom they diagnosed as having temporomandibular disorders. They suggest that, for tinnitus patients who have no neurological or ear disorders, a temporomandibular splint might be helpful. This is an interesting but very new proposal that would need to be fully evaluated.

GlossaryPlacebo An inactive substance or other sham form of therapy administered to a patient usually to compare its effects with those of a real drug or treatment.

Randomised control trial A study in which a number of similar people are randomly assigned to 2 (or more) groups to test a specific drug or treatment. One group (the experimental group) receives the treatment being tested, the other (the comparison or control group) receives an alternative treatment, a dummy treatment (placebo) or no treatment at all. The groups are followed up to see how effective the experimental treatment was.

Statistically significant The likelihood that a result or relationship is caused by something other than random chance.

Systematic review An electronic search is done to find all the studies that have already been conducted on a precise topic. Data from good quality studies are then combined for analysis. Systematic reviews can reveal more – and provide much stronger evidence – than individual studies.

Tinnitus Functional Index; Tinnitus Handicap Inventory; Tinnitus Severity Index Questionnaires aimed at evaluating the impact of tinnitus on a person’s daily life. The different questionnaires tend to use different evaluation systems and often look at different factors which may be contributing to tinnitus distress.

Vagus nerves A pair of long nerves running from the brain to the abdomen, providing a connection between the brain to the heart, intestine and other organs.